Extraction of copper from acidic liquors with a phenolic oxime



United States Patent Oflice 3,428,449 Patented Feb. 18, 1969 Claims ABSTRACT OF THE DISCLOSURE Process for the recovery of copper from an aqueous solution which comprises the use of certain substituted 2-hydroxy benzophenoximes either alone or in combination with certain a-hydroxy aliphatic oximes.

This application is a continuation-in-part of my earlier application Ser. No. 432,903, filed Feb. 15, 1965, now abandoned.

The present invention relates to the recovery of copper values from aqueous solutions and in particular to a liquid ion exchange extraction process.

In the mining of copper ores, large quantities of lowgrade copper-containing rock are removed from the mines, to expose the high-grade copper ores. In open pit operation, the tonnage of such rock exceeds the minea'ble ore by several fold. It is not economical to crush and mill this low-grade rock but, because of the large tonnage involved, an economical means of recovering the copper values is very desirable.

Some decades ago, it was found that if water, with or without acid present, is percolated through waste dumps of this rock that the copper is slowly dissolved. A dilute solution of copper sulfate can then be recovered from the bottom of these dumps. The problem then arises as to how to recover the copper from these solutions economically.

While the copper may be recovered by electrolysis, the current efficiency is so low and such large volumes must be handled that this process is economically prohibitive. The only method now in use for recovering this copper is 'by cementation. In this process, the dilute copper sulfate solution is passed over a bed of iron, usually scrap tin cans or sponge iron. The iron is oxidized and passes into solution while the copper is reduced to metal which is known as cement copper in the industry.

The cement copper is then refined either by smelting or by redissolving it in sulfuric acid and then electrolyzing the resultant strong copper sulfate solution.

It can thus be seen that a process which would convert weak copper sulfate solutions to strong copper sulfate solutions would be attractive if it could be cheaply done.

In attempting to apply the liquid ion exchange process to this problem several difficulties arise. In the first place, these dilute copper sulfate liquors are usually close to pH l.92.5 and contain large amounts of ferric and ferrous iron relative to the copper. The extractants known to date, such as naphthenic acids, aryl-sulfonic acids, fatty acids, modified fatty acids, and the like, either do not extract copper at this low a pH or extract the iron preferentially to the copper. While the pH can be raised to a value where these extractants will function efficiently by the addition of a base, such as lime, new problems are then encountered.

Because of the dilute nature of these solutions, the cost of lime is a major factor when compared to the value of the copper. In addition, when the pH is increased, the ferric iron precipitates as the basic iron sulfate as a gelatinous or fiocculent material which is extremely ditficult to settle or filter. Unfortunately, the ferric ions are the active lixivants in dump leaching so that the iron would have to be redisolved in acidified raflinate before it was pumped back to the dump. Since the precipitation of iron under these conditions is an irreversible process, a fresh source of iron would have to be utilized. It can easily be seen, from the above, that a process based on this scheme has not found favor in the industry.

I have now discovered that a class of substituted hydroxy *benzophenoximes are ideally suited for this purpose. The basic structure for the hydroxy benzophenoximes is as follows:

l NOH The compounds which are useful for the present invention have the above basic structure but are substituted by a saturated or ethylenically unsaturated aliphatic group or groups or the corresponding ether group or groups so as to have a suitable degree of solubility in a solvent to be used for the liquid-liquid ion exchange separation. These separations are usually conducted by having the ion exchange reagent dissolved in an essentially water-immiscible organic solvent. The preferred solvents of this type are the aliphatic hydrocarbon solvents such as the petroleum-derived liquid hydrocarbons, either straight chain or branched, such as kerosene, fuel oil, etc. Various aromatic solvents may also be used, such as benzene, toluene, xylene and other aromatic solvents, for example, those derived from petroleum. processing which may contain alkyl substituted aromatic materials. Typical of the latter solvents are those sold under the Panasol trademark by Amoco Chemicals Corporation, both in the RX and the AN series. These solvents are liquid and essentially insoluble in water. Generally, all these hydrocarbon solvents have specific gravities in the range of 0.65-0.95 and have a mid-boiling point in the approximate range of F.615 F. (ASTM distillation). In addition to the simple hydrocarbon solvents, the chlorinated hydrocarbons may also be used and in some instances may improve solubility. Accordingly, both the unsubstituted and the chlorinated solvents are contemplated by the term liquid hydrocarbon.

The benzophenoximes, which may be used in the present invention, are those which have sufficient solubility in one or more of the above solvents or mixtures thereof to make about a 2% solution and which are essentially insoluble or immiscible with Water. At the same time, the ion exchange reagent should form a complex with the copper which complex, likewise, is soluble in the organic solvent to at least the extent of about 2% by weight. These characteristics are achieved by having alkyl, ethylenically unsaturated aliphatic or ether substituents on either ring. Generally, it is necessary to have substituents which total at least 3 carbon atoms. This minimum may be obtained 'by means of a total of 3 methyl groups distributed on either one or on the two rings, by means of a methyl and an ethyl group, by means of a propyl group, etc. Usually it is preferred not to have more than 25 carbon atoms total in the substituents since these substituents contribute to the molecular weight of the oxime without improving operability. Large substituents, therefore, increase the amount of oxime for a given copper loading capacity. In general, the branched chain alkyl substituents effect a greater degree of solubility of the reagent and of the copper complex and, accordingly, these are preferred. A variety of typical compounds useful for the present invention include the following:

2-hydroxy-3 '-methyl-S-ethylbenzophenoxime 2-hydroxy-5-(1,1-dimethylpropyl)-benzophenoxime 2-hydroxy-5 l, l-dimethylethyl) --benzophenoxime 2-hydroxy-S-octylbenzophenoxime 2-hydroxy-5-nonyl-benzophenoxime Z-hydroxy-S-dodecyl-benzophenoxime 2-hydroxy-2,4-dimethyl-5-octylbenzophenoxime 2-hydroxy-2,3',5 -trimethyl-5-octylbenzophenoxime 2-hydroxy-3 ,5 -dinonylbenzophenoxime 2-hydroxy-4- 1, l-dimethylethyl -5- 2-pentyl -benzophenoxime 2-hydroxy-4'-( l, l -dimethylethyl) -5- (Z-butyl -benzophenoxime 2-hydroxy-4-dodecyloxybenzophenoxime 2-hydroxy-4'-(1,1-dimethylethyl)-5-methylbenzophenoxime 2-hydroxy-4',5-bis( 1,1-dimethylethyl)benzophenoxime A Wide variety of other compounds within the scope of the present invention may, likewise, be devised and it is a simple matter to determine their effectiveness by simply testing the solubility of the compounds in one or more of the above hydrocarbon solvent or mixtures thereof. In general, the aromatic or aliphatic substituted aromatic hydrocarbon solvents are preferred from the standpoint of improved solubility. The Q-hydroxy benzophenoximes are preferably used in an amount of about 2 to 50% by weight and more preferably about 2 to 25% by weight based on the weight of the organic phase.

The extractants of the present invention may be made by any of a variety of classical synthesis routes. These routes involve the formation of the benzophenone from known starting materials followed by the conversion of the benzophenone to the benzophenoxime. Two suitable methods of making the benzophenone include the following: One such method is that reported by Newman (J. Org. Chem., 19, 9 85-l002 (21954)). This method involves the reaction of a phenol with a benzotrichloride in accordance with the following equation:

OH C013 OH A second method involves the rearrangement where a phenolic ester is rearranged to a benzophenone in accordance with the following equation:

Typical commercially available p-substituted alkyl phenols which may be used in these methods include the following:

sec-butylphenol tert-butylphenol 2,4-di-tert-butylphenol octylphenol nonlyphenol 2,4-dinonylphenol dodecylphenol amylphenol Representative of other starting phenols are those having the following groups in the para position:

CH3 CHa )-OI-Iz( J-CI-l'a CH3 QH CI E CH3-CCH2C-CH3 H HzOR i I CH3(|]CH2-C}-CH3 CH 0 H 0 (J 11"" and the like where R' and R"" are alkyl groups of l to about 8 carbon atoms for example. Of the two methods described above for the preparation of the benzophenones, the first is preferred as the second involves some side reactions which reduce yields.

A third method of producing compounds of this type is illustrated in the following sequence:

The particular method which may be employed to produce the extractant may depend upon the particular compounds available as starting materials and the efficacy of the particular method as applied to such starting materials. However, all of the compounds useful in the present invention may be produced by one or more of these methods in combination with classical synthesis methods which may be used for the preparation of starting materials for the final reactions.

The benzophenoximes useful in the present invention are prepared from the described benzophenones by reaction of the latter with a hydroxylamine salt under reflux conditions. Such reaction can be carried out by refluxing the reactants in an alcohol such as methanol or ethanol and adding pyridine or sodium acetate to combine with the acid associated with the hydroxylamine.

The preferred substituted hydroxy benzophenoximes useful in the present invention have the following formula:

NOH

in which R and R may be individually alike or different and are saturated aliphatic groups, ethylenically unsaturated aliphatic groups or saturated or ethylenically unsaturated aliphatic ether groups (i.e. OR") and m and n are 0, 1, 2, 3 or 4 with the proviso that m and n are not both 0. In such preferred extractants, the total number of carbon atoms in R and -R' is from 3 to 25, R and R contain 1 to 25 carbon atoms when saturated aliphatic and R and R contain 3 to 25 carbon atoms when ethylenically unsaturated. Preferably, the position ortho to the phenolic OH substituted carbon atom is unsubstituted and also preferably the positions ortho to the oxime carbon atom on the other aromatic nucleus are unsubstituted. Branched chain saturated aliphatic hydrocarbon substituents are preferred.

As indicated from the representative compounds set forth herinabove and the described starting phenols and the like, various alkyl groups can be used as R and R. And as set forth, such groups may be branched or straight chain. Various ethylenically unsaturated groups can also be used as R and R and the same may be branched or straight chain. Representative of such groups are pentenyl, hexenyl, octenyl, decenyl, dodecenyl, octadecenyl, and the like. It is preferred that such groups contain less than about 2 double bonds and more preferably a single double bond. The R" portion of the ether groups can be the saturated and ethylenically unsaturated aliphatic groups as described above. The R portion of the said ether groups is preferably an alkyl group. In addition, the saturated, ethylenically unsaturated and ether groups may contain inert substituents such as halogen, ester, amide, and the like. Likewise, the aromatic nuclei can contain inert substituents. By inert is meant that the said substituents do not affect the solubility, stability or extraction efficiency of the compounds to any significant extent.

As indicated above, these benzophenoximes are particularly desirable for the extraction of copper from acid solutions. In present day commercial operations, most of the available copper solutions have pHs in the approximate the oxime as follows: Into a 100 ml. round bottom flask equipped with a reflux condenser and thermometer, 19.2 grn. (0.05 mole) of 4-dodecy1oxy-2-hydroxybenzophenone, 13.9 gm. (0.2 mole) of hydroxylaminehydrochloride, 15.9 gm. (0.2 mole) of pyridine and ml. of absolute methanol were added. This mixture was then refluxed for 4 hours (83 C.) and allowed to cool to ambient temperature overnight. The product was isolated by extracting the mixture with water and ether and then washing the ether phase twice with water, twice with dilute hydrochloric acid and four times with water, drying the ether phase over Na SO and stripping off the ether under vacuum. Inspection of the infrared absorption spectra of the resultant product showed that a considerable amount of the ketone had been converted into the oxime.

(2) Extraction of a copper solution with 4-dodecyloxy- Z-hydroxybenzophenoxime 10 ml. of copper sulfate solution (0.033 M Cu++, 0.5 M N21 SO and 20 ml. of a 5% solution of 4-dodecyloxy- 2-hydroxybenzop'henoxime in 1,1,2-trichloroethane was added to a series of 250 ml. separatory funnels. Aliquots of acid or base were then added to various separatory funnels to adjust the pH and then the mixture was equilibrated by shaking for one minute. The results obtainer are given in the following table:

range of 1.7 to 3.0. In addition, these solutions also generally contain iron. Under these circumstances, the present invention permits recovery of the copper without significant contamination with iron since these benzophenoximes are very selective toward copper at these low pHs. At higher pHs, namely in the range of 3-7, these compounds have gradually reducing selectivity toward copper and begin to extract iron as well. Accordingly, these higher pHs may be used where (a) the copper solution has very little iron, (b) it is desired to extract both copper and iron, and (c) Where it is possible to strip iron from the organic phase before stripping copper.

The above pHs refer to the acidity of the solutions before extracting. Since the extraction results in the liberation of hydrogen ions, the pH decreases during extraction. Equilibrium pHs generally are in the range of 1.4- 5.0. With copper solutions having relatively low pHs to begin with and with high initial copper concentrations, it is evident that the pH may be reduced to a point approaching 1.4-1.5 even though the copper extraction is far from complete. In such instances, it may be desirable to adjust the pH either initially or during the course of the extraction to effect desirable rates of extraction and desirable degrees of depletion of the starting solution. Whether the pH of such a solution is adjusted before or during the extraction may depend on the relative iron content.

The following examples will illustrate the preparation of typical extractants and also the process of effecting the extraction using such extractants. It is to be understood, however, that these examples are illustrative only and not as limiting the invention.

EXAMPLE I (1) Preparation of 4-dodecyloxy-2-hydroxybenzophenoxime 4-dodecyloxy-2-hydroxybenzophenone was prepared as described in U.S. Patent 2,861,053. It was converted to It is seen from this table that the o-phenolic oximes are very efiicient copper extractants down to a pH of at least 2. 0 and somewhat below. This is the pH that is of interest for the extraction of copper from heap leaching.

EXAMPLE II (1) Preparation of 2-hydroxy-4'-(1,l-dimethylethyl)-5- (Z-pentyl)-benzophenoxime 468.1 grams (2.38 moles) of p-t-butyl benzoyl chloride, 390.7 grams (2.38 moles) of p-s-amyl phenol were combined in a 2 l. flask and heated to 200 C. for 1 /2 hours. The product was cooled and was taken up in diethyl ether and washed once with water, twice with dilute NaOH and then three times with water and finally dried over sodium sulfate. Removal of the ether under vacuum gave 768 grams of a light-colored residue. The residue was then distilled to give 674.3 grams of a water-white liquid collected at 209 to 220 C. at 50 microns pressure.

324.4 grams of the above material (1 mole), grams of aluminum chloride (1.05 moles) and 400 ml. of phenyl chloride were added to a 2 liter flask equipped with a thermometer, stirrer and reflux condenser. The temperature immediately rose to 60 C. and heating was started. The mixture was refluxed for of an hour and then poured over ice. This aqueous slurry was then heated to decompose the complex. The product was then extracted with Skellysolve B and washed twice with dilute hydrochloric acid and five times with water. The solvent was stripped off under vacuum to leave a residue which was saponified by adding 132 grams KOH dissolved in ml. of water, 700 ml. of isopropanol, 300 ml. of methanol, under reflux for 24 hours. The product was then poured into 12 liters of Water and extracted with Skellysolve B. The product was washed three times with dilute NaOH- NaCl, four times with water, two times with dilute HCl and five times with water and then dried over sodium sulfate. The solvent was then distilled off and the residue Vacuum distilled to yield 82.5 grams of product collected at 183 to 193 C. at '80 microns. This benzophenone was then converted to the oxime as previously described.

(2) Extraction of copper The liquid ion exchange circuit consisted of three stages for extraction and four stages for stripping. Provisions were made to add a base (0.25 N NH solution) to the first and second stage mixes for pH control. The pHs for the first aqueous stage, the second aqueous stage and the third aqueous stage (raffinate) were measured and recorded. Stripping was accomplished in four stages, using sulfuric acid solutions. The initial acid concentration was 3 01 grams H 80 per liter and the pregnant solution from stripping was reused as the stripping solution. The extractant was composed of a 5% by volume solution of the extractant in kerosene. Aqueous feed solutions were made up by dissolving copper sulfate and sodium sulfate in water and adjusting the pH to 2122.2 sulfuric acid. The iron in the solution was dissolved ferric sulfate. The circuit was operated with the aqueous solution in the continuous phase to minimize short circuiting.

The extraction was conducted in the three stages with different feed rates and the results are indicated in the following table:

3 STAGE EXTRACTION, 4 STAGE STRIPPING [Ambient Temperature=30 0.]

Extraction:

Hours of operation 7 14 Aqueous Feed, oc./mln 42 50 54 Aqueous Feed, g. Cu/l 0. 98 1.00 1. 02 Aqueous Feed, g. Fe/L. 1.08 0.50 0. 50 Aqueous Feed, pH. 2. 18 2. 23 2. 16 Aqueous pH, 1st State 2.02-2.10 2. 08-2. 20 2 002. 18 Aqueous pH, 2nd Stage 2. 05-221 2. 00-2. 2 06-2. 23 Aqueous pH, Rafiinate 1. 982. 06 1.98-2.20 1 90-216 Ratfinate, g. Cu/l 0.08 0. 11 0. 15 Raftinate, g. Fe/l- 1. 04 0. 49 0. Organic, cc /min. 27. 2 27.3 24. 8

Organic, g. Cu 0.15 0. 15 0. 18

Organic, g. Fell Cu Extraction, percent- Fe Extraction, percent 3. 7 1.0 0

Stripping:

Loaded Organic, g. Cu/l 1. 1. 93 2.03 Loaded Organic, g. Fe/l 0.05 0. 04 0. 025 Strip Solution, cc./min 6.7 6. 15 G. 4 Strip Solution, g. Cu/l 12. 4 20. 1 30.0 Strip Solution, g. Fell 0. 18 0. 31 Strip Solution, g. H2/SO4/l.. 287 277 264 Preg. Solution, g. Ou/l 18.1 20.1 34. 1 Preg. Solution, g. Fe/l. 0. 14 0. 27 0.33 Preg. Solution, g. H2SO4/l 280 270 256 1 Nil.

These results show that good copper extraction is obtained at all of these levels of feed. Iron extraction into the organic phase is very low and high concentrations of copper in the stripping solution can be obtained as is evident by the final result which showed 34.1 grams of copper per liter. This shows that stripping can be accomplished with a copper-saturated acid solution, thus giving copper sulfate crystals as the final product. It is thus possible to produce a solution suitable for electroplating of copper. In the final fourteen-hour operation, the iron extraction based on assays of the feed and ratfinate was zero. The slight amount of iron shown in the loaded organic may be due to aqueous entrainment. Minor amounts of copper are shown in the raffinate but when the raffinate was contacted within an additional stage of extraction, it was found that a very high percentage of the remaining copper could be extracted. Thus, in a fourstage extraction, copper recoveries of the order of 95% or better are obtainable.

EXAMPLE III (1) Preparation of 2-hydroxy-2,4',5'-trimethyl-5- octylbenzophenoxirne 266.7 grams of aluminum chloride (2 moles) and 600 ml. of carbon tetrachloride were added to a 1 liter flask equipped with a stirrer, addition funnel and a temperature controller. 120.2 grams (1 mole) of pseudocumene dissolved in 200 ml. of carbon tetrachloride was then added to the flask at 37 to 42 C. over a 1 hour period. Reaction was continued for an additional 2 hours at this temperature. The product was cautiously added to water and the temperature kept in the range of 60 to by the addition of ice. Stirring was continued an additional 5 minutes and it was cooled to 30 by the addition of more ice. The product was then extracted with diethyl ether-Skellysolve B and was washed with water until neutral. It was then dried over calcium chloride over night. The product was filtered and the filtrate was stripped of solvent to give 208.2 gm. of a crude 2,4,5-trimethyl benzotrichloride having a chlorine content of 36%.

86.6 grams (0.65 mole) of aluminum chloride and 100 ml. of carbon disulfide were added to a 1 liter flask equipped with a stirrer, addition funnel and a thermometer. The mixture was cooled to 0 to 5 C. and 103.2 grams (0.5 mole) of octyl phenol was added, the octyl phenol comprised a mixture of phenols substituted in the para position with branched chain 8 carbon atom alkyl radicals, about of such radicals having the structure CH3(IJCH3 Ht'JH CHa( JCHa 156.2 grams of crude 2,4,5-trimethyl benzotrichloride (0.5 mole assuming 76% purity) and ml. of carbon disulfide were then added over a 15 minute period at 0 C. and this temperature maintained an additional 3 hours. 200 ml. of absolute methanol was then added at 0 C. followed by 250 ml. of water. This mixture was then poured into 1 liter of water and heated to 47 and was then allowed to cool over night. The product was then extracted with diethyl ether and Skellysolve B and washed with water until neutral. It was then dried over sodium sulfate. The sodium sulfate was filtered off and the solvent distilled off. The residue was distilled to yield a fraction containing 83.3 grams of 2-hydroxy-2',4',5-trimethyl-5-octylbenzophenone. This product was converted to the corresponding oxime by a standard method.

(2) Extraction of copper The above oxime was then used for extracting copper from 0.049 molar copper sulfate solution. The oxime was used in the form of a solution composed of 5 grams of Y the oxime diluted to 100 ml. with kerosene. 10 ml. of the 0.049 molar copper sulfate solution was diluted with 10 ml. of 0.05 molar sodium bisulfate. A series of extractions were conducted in separatory funnels using 10 ml. of the extractant solution. The separatory funnels were shaken for the time periods indicated in the following table and the aqueous phase was then separated from the organic phase. The results are indicated in the following table:

Time pH P.p.m. Cu

in organic A 1min 2.28 1,180 B... 5min 2.19 1,820 C 10 rnin 2.18 1,940 D miu 2.19 1, 935

EXAMPLE IV sodium sulfate. The mixed solution contained 3,180 p.p.m. copper. The extractions were conducted in separatory funnels by mixing the aqueous and organic solutions and shaking them in a separatory funnel for the indicated time periods. The pH was adjusted by the addition of 1 EXAMPLE VI Z-hydroxy3,5-dinonylbenzophenoxime was prepared by the method. described in Example V using 3,5-dinonylphenol (the nonyl groups were random-branched alkyl 5 radicals). Five grams of the above oxime was dissolved the fi i fi fi i f i blsulfate' The in an alkyl substituted aromatic hydrocarbon solvent S are m e m e 0 owmg ta (Panasol AN-l). It was used to extract copper from 0.035

ML, ML, pH P.p.m. Cu Organic Cu S in organic EXAMPLE V 20 molar copper sulfate containing 10 grams of sodium sul- (1) Preparation of 2hydroxy-Sdodecylbenzophenoxime 2-hydroxy-5-dodecylbenzophenoxime was prepared by the following method: 346.7 grams (2.6 moles) of aluminum chloride and 1900 ml. of carbon disulfide were added 25 to a 5 liter round bottom flask equipped with a stirrer, thermometer and addition funnel. The mixture was cooled to 0 C. 524.8 grams (2 moles) of dodecylphenol (available from General Analine and Film-the dodecyl phenol comprised a mixture of monoalkyl phenols, predominantly para substituted, the chains being random-branched alkyl radicals) was mixed with 100 ml. of carbon disulfide and then added at 0 to the flask. The flask was cooled to to 391 grams ('2 moles) of benzotrichloride was then added at temperatures of 15 to 20" over a period of 13 minutes. The flask was warmed to 0 to 5 and held for 1 hour. One liter of methanol was added at 0 to 5 followed by 500 ml. of water at the same temperatures. The mixture was heated and at C., steam was passed through and continued to heat until a temperature of 100 C. was reached. The mixture was then cooled and poured into dilute hydrochloride acid and extracted with diethyl ether and dried over sodium sulfate. The solvent was stripped off and the residue was stripped and a fraction of 288.7 grams of 2-hydroxy S-dodecylbenzophenone was recovered. This benzophenone was converted to the oxime by a standard method.

(2) Extraction of copper Time, pH P.p.m.

min. Cu ORG ML, ML, M1, M1., Time, M Cu organic Cu SOL 0.1 M H2O min. pH aqueous EXAMPLE VII (1) Preparation of 2-hydroxy-S-nonylbenzophenoxime Seven hundred fifty parts ethylene dichloride and 103 parts powdered aluminum chloride were charged to a glass-lined reactor equipped with an EC] scrubbing system. After cooling the above materials to 37 C., a mixture of 178 parts nonylphenol as used in Example IV and 108 parts ethylene dichloride was pumped into the same over a period of 23 minutes. The pump and lines were rinsed with 20 parts ethylene dichloride at which point the reaction mixture had a temperature of 35 C. After 10 minutes, 140 parts benzotrichloride were pumped into the reaction mixture over a 10 minute period and the pump and lines were again rinsed with 20 parts ethylene dichloride. The reaction mixture temperature was then -23 C. After allowing the materials to react for 15 minutes, parts of methanol were pumped into the same over a 20 minute period. The temperature rose to 9 C. at which time 200 parts water were added. The reactor was then opened and an additional 560 parts (approximately) of water were added at which point the reaction mixture had a temperature of 24 C. The water layer was siphoned off the top and approximately 920 parts more water was added as a second wash. After about one hour, the water layer was again siphoned off. At this point, 280 parts more water and 30 parts sodium hydroxide flakes were added to the reaction mixture. The resulting admixture was heated with steam to distill off the ethylene dichloride (a pot tem perature of 101 C. was reached over a period of about five hours). Distillation was stopped, cooling was applied to the reactor and, when the temperature reached 63 C., 300 parts n-hexane were added. After the addition of the n-hexane, the temperature was 38 C. The mixture was allowed to separate for 50 minutes and then the water layer was drained out of the bottom. Two hundred eighty parts water and six parts sodium hydroxide flakes were added to the hexane solution with agitation for one minute at 38 C. The admixture was allowed to settle for 35 minutes and the water layer was again drained out of the bottom. The remaining organic layer was steam distilled to remove the hexane (after 2% hours, the temperature was about 101 C. and most of the hexane had distilled off). Vacuum was applied and the temperature was increased to 175 C. over a four hour period to yield 220 parts of product. Two hundred eighteen parts of this product were charged to a still equipped with a large capacity vacuum pump. The product was heated slowly under vacuum for /2 hours until 20 parts (approximately were obtained as a forecut (conditions were pot temperature 213 C., overhead temperature 205 C., 2.3 mm. Hg vacuum). Distillation was continued for four more hours until 151 parts distillate were collected (conditions were pot temperature 236 C., overhead temperature 210 C., 1.4 mm. Hg vacuum). Distillation was stopped at this point leaving 36 parts residue. Analysis of the main distillation cut showed that it consisted of 96% of the desired 2-hydroxy-5-nonylbenzophenone, 1.5% nonylphenol and trace amounts of other materials.

One thousand grams (3.08 moles) of the above-prepared Z-hydroxy-S-nonylbenzophenone, 32.0 grams (4.61 moles) hydroxylamine hydrochloride, 416 gram (5.07 moles) sodium acetate and 400 grams absolute methanol were combined in a 5 1. round bottom flask equipped with a stirrer, thermometer and reflux condenser. The reaction mixture was heated to reflux which was continued for 31 hours. The resulting reaction mixture was poured into water, extracted with ether and the ether solution was washed with water until neutral. The ether solution was then washed with a saturated aqueous NaCl solution, dried over Na SO and stripped of ether at 60 C. (10 mm. Hg) to yield 995.3 grams of 2-hydroxy-5-nonylbenzophenoxime.

(2) Extraction of a copper solution with 2-hydroxy-S-nonylbenzophenoxime Ten milliliters of a 10% wt./vol. solution of the oxime in kerosene (10 grams oxime diluted to 100 ml. with kerosene) were placed in a 60 ml. separatory funnel. Twenty milliliters of an aqueous solution containing 4 gm./l. Cu+ and having a pH of 1.90 (prepared by diluting 15.7 gm. CuSO -5H O to one liter with water and adjusting the pH with cone. H SO were then added. The separatory funnel was shaken for two minutes at ambient room temperature and the aqueous phase was separated from the organic phase. The above procedure was repeated three more times adding fresh 20 ml. portions of the copper solution each time. The pH of the last aqueous phase separated from the organic phase was 1.89 indicating that the organic phase was substantially loaded with copper.

The organic phase analyzed 4310 ppm. Cu.

A further important aspect of the present invention is the discovery that the use of the benzophenoximes of the present invention, in combination with certain aliphatic oximes, results in a phenomenal improvement in the kinetics of the extraction. The extraction of copper values from aqueous solutions using these a-hydroxy oximes alone is preferably conducted at high pHs above 7 because of improved yields and better selectivity with respect to iron at these pHs as compared with low pHs. The 2-hydroxy benzophenoximes as described and shown above, however, are very effective at low pHs but the kinetics of the extraction of these low pHs with the 2- hydroxy benzophenoximes is not as good as it is with the tit-hydroxy aliphatic oximes of my prior application.

Surprisingly, however, it" has been found that when the ahydroxy aliphatic oximes are employed, in combination with the Z-hydroxy benzophenoximes at low equilibrium pHs, for example, in the range of 1.4-2.3 pHs, the kinetics of the extraction are very materially improved without any serious effect on the selectivity of the extraction with respect to iron. The combination of the two reagents provides important advantages as to:

(1) Preferential extraction of the copper,

(2) Extraction of the copper from the aqueous solution at low pH values (copper solutions normally exist at low p (3) Improved rate of copper extraction with respect to time,

(4) Improved recovery from the organic phase, and

(5) Greater economy.

The a-hydroxy aliphatic oxime extractants which may be used for this purpose have the following general formula:

where R R and R may be any of a variety of organic radicals such as aliphatic and alkylaryl radicals. R may also be hydrogen. Preferably, R and R are unsaturated hydrocarbon or branched chain alkyl groups containing from about 6 to 20 carbon atoms. R and R are also preferably the same and when alkyl are preferably attached to the carbons substituted with the OH and NOH groups through a secondary carbon atom. It is also preferred that R is hydrogen or unsaturated hydrocarbon or branched chain alkyl groups containing from about 6 to 20 carbon atoms. The a-hydroxy oximes also preferably contain a total of about 14 to 40 carbon atoms. Representative compounds are l9-hydroxyhexatriaconta- 9,27-dien-18-oxime, 5,10-diethyl 8-hydroxytetradecan-7- oxime, and 5,8diethyl-7-hydroxydodecane-6-oxime. The latter compound has the following structural formula:

Representative of other monoand polyunsaturated radicals are heptenyl, octenyl, decenyl, octadecenyl, octadecynyl and alkyl substituted radicals such as ethyloctadecenyl. Representative of other monoand polyalkyl substituted saturated radicals are ethylhexyl, diethylheptyl, butyldecyl, butylhexadecyl, ethylbutyldodecyl, butylcyclo hexyl and the like. The R R and R groups may contain inert substituents.

The a-hydroxy oxime extractants are also characterized as having a solubility of at least about 2% by weight in the hydrocarbon solvent used to make up the organic phase and substantially complete insolubility in water. In addition, it is believed that the copper values and the ahydroxy oxime extractant form a complex during the initial extraction step and such complex, when formed, should also have a solubility of at least about 2% by weight in the hydrocarbon solvent.

The relative amounts of the two extractants can be varied widely as examples hereinafter will demonstrate. Even minute quantities of the a-hydroxy aliphatic oxime are beneficial. However, it is preferred to employ it in the range of l to by weight based on the weight of the 2-hydroxy benzophenoxime, with best results obtainable in the range of 15-50%. The amount of the extractants in the organic solvent likewise can vary within considerable limits. In general, however, the concentration of total oxime is in the range 225%, based on the weight of the organic extracting solution, preferably in the range of 515%.

EXAMPLE VIII A series of extractions were conducted on an aqueous copper sulfate solution in which the copper was extracted from the aqueous solution by means of a mixed solution of 2-hydroxy-5-dodecylbenzophenoxime as prepared in Example V and 5,8-diethyl-7-hydroxydodecane-6-oxime in an alkyl substituted aromatic hydrocarbon solvent. The concentration of the copper in the aqueous solution used as a starting material as well as the concentrations of They likewise 3,428,449 13 the respective extractants and the aqueous to organic These tables show that the combination of the two exime of extraction tractants enhances the rate of extraction.

show that good extraction can be achieved in five minutes TABLE 1 M1. (B) (On) Time, Aq. A/O percent pH org., min.

p.p.m.

M1,, (Ou org. aq.M

percent ratios together with the recovery and t are indicated in the following tables.

nmwmmmmmwwwmwmfimmwmmwem 7777788B5789368913581235 LLLLLLLLLLLLLLLLLLLLLLLL 5555000055551111 .n h h h 55552222111100000000 min.

pH (Cu) org. Time,

p.p.m.

=2-hydroxy E-dodeeylbenzophenoximine. B 5,8-diethy1-7-hydroxydodeeane-fi-oxime.

TABLE 2 Ml, (Cu- ML, A/O (B) org aq. M Aq. percent 1 None.

percent 5555000000000000 0000LLLLZZ2Z5555 H%WM= UMWM%%NK UWK E Q M654777688888888 7 0 505000 7HW8RNWWWW7S7888 LLLLLLLLLLLLLLLL an-30505050506050 ZZLLZZLLnAZLLZZLL 2222222222222222 mmmmmmmmwwmwmmmm 0000000000000000 0 0 00000 000000 mmmw11111m111111 Time, min.

phenoxime.

TABLE 3 Ml, A/O (B) pH (Cu) org. Aq. percent p.p.m.

=2-hydroxy S-dodecylbenzo B =5,8-diethy1-7-hydroxydodecane-ooxime.

M1., (Ou++) org. aq. M

N OTE .A

percent 000000000000 LLLL2 2 2 2 5 5 5 5 0000 1111 LLLLLLLLLLLLLLLL 50 50 50 5O 05ZL052LO52L052L 1 1 1 1 2222222222222222 mmmmmmmmmmmmmmm ooooooooooooooow pH (Cu)org. Tirne,

p.p.m. mm.

TABLE 4 ML, A/O (B) percent =2-hydroxy fi-dodecylbenzophenoxime. B =5,8-diethyl-7-hydroxydodecane-6eoxime.

ML, (Cu++) org. aq. M

NOTE .A

percent LLLLLLLLLLLLLLLL 5 5 5 5 5052505250525052 ZLQQQLQQZLQQZLQO 000000000 mmmwmmmlllllllll NoTE.-A=2-hydroxy 5-dodecylbenzophenoxime.

B 5,8-diethyl-7-hydroxydodecane-6-oxime.

15 or less. They further show that considerable variations in the concentrations of the reagents may be used as well as considerable variation in the relative ratios of the reagent.

While the above description has been with particular reference to specific examples, it is to be understood that the invention is not restricted thereto but may be varied within the scope of the appended claims.

Now, therefore, I claim:

I. A process for the recovery of copper values from an aqueous solution comprising: (1) contacting said aqueous solution with an organic phase comprising a liquid, essentially water-immiscible organic solvent and a 2-hydroxy benzophenoxime selected from the group consisting of alkyl substituted, ethylenically unsaturated aliphatic substituted and alkyl or ethylenically unsaturated aliphatic ether substituted 2-hydroxy benzophenoximes to extract at least a portion of the copper values into the organic phase, said 2-hydroxy benzophenoxime having a solubility of at least about 2% by weight in the liquid, essentially water-immiscible organic solvent, (2) separating the resultant copper-pregnant organic phase from the aqueous phase, and (3) recovering copper values from the organic phase.

2. A process according to claim 1 in which the copper values are stripped from the organic phase by means of an acid.

3. A process according to claim 2. in which the acid is sulfuric acid.

4. A process according to claim 1 in which the aqueous solution being extracted has a pH in the range of 1.7 to 7.0.

5. A process according to claim 1 in which the essentially water-immiscible organic solvent is a liquid hydrocarbon.

6. A process according to claim 5 in which the liquid hydrocarbon is kerosene.

7. A process according to claim 1 in which the essentially water-immiscible organic solvent is a liquid aromatic hydrocarbon.

8. A process according to claim 1 in which the 2-hydroxy benzophenoxime has the formula in which R and R may be individually alike or dilferent and are saturated aliphatic groups of 1-25 carbon atoms, ethylenically unsaturated aliphatic groups of 3-25 carbon atoms or OR where R is a saturated or ethylenically unsaturated aliphatic group as defined, m and n are 0, 1, 2, 3 or 4 with the proviso that both are not and the total number of carbon atoms in R and R is from 3-25.

9. A process according to claim 8 in which R is an ethylenically unsaturated group.

10. A process according to claim 8 in which R is an unsubstituted branched chain aliphatic hydrocarbon group.

11. A process according to claim 8 in which R is an unsubstituted branched chain hydrocarbon group.

12. A process according to claim 11 in which at least one R group is in the position.

13. A process according to claim 1 in which the 2-hydroxy benzophenoxime is 2-hydroxy-5-dodecylbenzophenoxime.

14'. A process according to claim 1 in which the 2-hydroxy benzophenoxime is 2-hydroxy-5-dodecyloxybenzophenoxime.

15. A process according to claim 1 in which the 2-hydroxy benzophenoxime is Z-hydroxy-S-nonylbenzophenoxi-rne.

16. A process according to claim 1 in which the 2-hydroxy benzophenoxime is 2-hydroxy-2',3,5'-trimethyl-5- octylbenzophenoxime.

17. A process according to claim 1 in which the 2- hydroxy benzophenoxime is 2-hydroxy-4-(1,1-dimethylethyl) -5-(2-pentyl -benzophenoxime.

18. A process according to claim 1 in which the aqueous solution has a pH in the approximate range of 1.7-3.0, the liquid, essentially water-immiscible organic solvent is kerosene, the Z-hydroxy benzophenoxime is 2-hydroxy-5- dodecylbenzophenoxime, the said phenoxime is present in the organic phase in an amount of about 2 to 50% by weight and the copper values are recovered by stripping the copper-pregnant organic phase with sulfuric acid.

19. A process according to claim 1 in which the organic phase also contains an a-hydroxy aliphatic oxime having a solubility of at least about 2% by weight in the liquid, essentially water-immiscible organic solvent and having the formula:

where R and R are organic radicals and R is selected from the group consisting of hydrogen and organic radicals.

20. A process according to claim 19 in which the a-hydroxy aliphatic oxime is employed in a proportion of 1 to 100% by weight based on the weight of the 2- hydroxy benzophenoxime.

21. A process according to claim 19 in which the aqueous solution also contains iron and has a pH in the approximate range of 1.7-3.0.

22. A process according to claim 19 in which the essentially water-immiscible organic solvent is a liquid hydrocarbon, the organic phase contains 2 to 25% by weight of 2-hydroxy-5-dodecylbenzophenoxime and 15 to 50% of 5,8-diethyl-7-hydroxydodecane-6-oxime based on the weight of the Z-hydroxy-S-dodecylbenzophenoxime.

23. A process according to claim 22 in which the pH of the aqueous solution being extracted is in the approximate range of 1.7 to 3.0 and the liquid hydrocarbon is kerosene.

24. A process according to claim 19 in which the essentially water-immiscible organic solvent is a liquid hydrocarbon, the organic phase contains 2 to 25 by weight of 2 hydroxy 2',3,5'-trimethyl-5-octylbenzophenoxime and 15 to 50% by weight of 5,8-diethyl-7-hydroxydodecane-6-oxime based on the weight of the 2-hydroxy-2',3', 5-trimethyl-5-octylbenzophenoxime.

25. A process according to claim 19 in which the essentially water-immiscible organic solvent is a liquid hydrocarbon, the organic phase contains 2 to 25% by weight of 2-hydroxy-4'-( 1,1-dimethylethyl) -5-(2-pentyl)-benzophenoxime and 15 to 50% by weight of 5,8-diethyl-7- hydroxydodecane-6-oxime based on the weight of the 2- hydroxy-4'-( 1, 1-dimethylethyl) -S- 2-pen ty1) benzophenooxime.

References Cited UNITED STATES PATENTS 3,294,842 12/1966 Swanson -117 3,224,873 12/ 1965 Swanson 751 17 3,276,863 10/1966 Drobnick et al 75-117 HYLAND BIZOT, Primary Examiner.

TERRY R. FRYE, Assistant Examiner.

US. Cl. X.R. 

